Superduty dump build

[Iplayfarmer]

You are half right.

That is always likely.

I think what we both admit is that I've only answered half the question. Keep in mind that I'm considering that there are two parts to the question.

1) How much force can the ram exert in a vertical direction?
2) How much vertical force is required to begin dumping the bed?

If the answer to question 1 is bigger than the answer to question 2 the project is a success and everyone is happy. If not, then some re-engineering needs to happen.

The angle needed to be used is the angle from the green "imaginary" line to the cylinder. And NOT the angle from the cylinder to the bed.

I disagree. The angle needed is actually the angle of the cylinder relative to gravity. That's why your mention of the level bed is so important.

The relation between the bed pivot and the upper ram pin may come into play when determining how much force is needed to begin dumping the bed (question 2), but the vertical force of the ram is only affected by the elevation of the bottom relative to the top as compared to the length of the ram itself. An example of this is if you dropped the bottom of the ram by 19" your ram would be straight up and down. Without changing the angle represented by the green line, you'd have substantially changed the amount of vertical force acting on the bed.

This will give the vertical lift at THAT point. But then theres the whole issue of how far forward on the bed the cylinder is mounted in relation to the rear pivot and CL of the bed itself. If the bed is 100" long for example, and the cylinder is hooked @ 50", the dump capacity would simply be the SIN of the angle mentioned above x the cylinder force. BUT if the cylinder is mounted farther forward of the rear pivot, like at 60", this increases the capacity by 6/5ths. And if farther back, it reduces capacity.

Now we're talking answers to question 2 from above. I agree with you completely here. The further forward on the bed you get, the less force is needed from the ram to get the bed to start moving. I'm still trying to find a way to calculate the force needed to raise a dump bed. I'm sure the result is going to be expressed in foot-pounds as it's a rotational force. It's going to depend on the length of the bed, the location of the bed pivot, and the location of the upper ram pin.

 

[BHD]

when I bought my 1978 one tone with a 12 foot flat bed,
I (gas was cheap) drove to Surplus Center in Nebraska, and picked up what was called a 5 ton wagon hoist, (there current offering)
Surplus Center - 5 TON WAGON/UNIVERSAL HOIST H-5/BHK-70 and I bought a electric 12 volt power pack, simular to Surplus Center - 12 VDC 1.4 GPM 2000 PSI SPX SA POWER PACK and mounted that on my truck,

It has been very handy over the years, hauling and dumping many many things, I put my hinges at the rear of the box, (extended the frame a little), so there is no tail drop when lifting, (my thought was if I have a trailer on I could still dump gravel or grain, considered making a dump trailer at one time, never did it, and figured I could use a selection valve and use the power pack to dump the trailer as well, (in the years never really needed the zero drop on the bed, and at times wish I would have put the pivot up a Little so the bed would lower some, when raised, (could make it easer to line up to load some thing on easer),
(the hoist design did not have any problems with drive line, and only raised the box/bed about 1/2")

I had tool boxes on my truck as well for many years similar to what you have and had very little problem with things sliding in them, (guess there were to full of junk),
I would strongly suggest any one with a flat bed add a hoist to the truck makes life so much easer,

 

[LD1]

I disagree. The angle needed is actually the angle of the cylinder relative to gravity. That's why your mention of the level bed is so important.

The relation between the bed pivot and the upper ram pin may come into play when determining how much force is needed to begin dumping the bed (question 2), but the vertical force of the ram is only affected by the elevation of the bottom relative to the top as compared to the length of the ram itself. An example of this is if you dropped the bottom of the ram by 19" your ram would be straight up and down. Without changing the angle represented by the green line, you'd have substantially changed the amount of vertical force acting on the bed.

A little give and take is always good. Who knows, we may both learn something from this.

But I am still in disagreement with you, sort of. While the angle of the cylinder may indicate "true" vertical force, using that "true" vertical force of ~20000lbs you calculated earlier would assume that the bed is level. BUT the effective angle of the bed is the "green" line. So that "true" vertical component can only be used if the green line is horizintal. (IE: the rear pivot and the cylinder-bed pivot are equal distances below the bed.

To illustrate my point, lets exaggerate a bit. Lets say the cylinder is mounted on a 10* angle and the rear pivot were dropped down REALLY low to create say a 12* "green" line. IE moving the base of the cylinder above the "green" line. The vertical component would still be 17% of the 49000lbs of avaliable force, or about 8000lbs. But what would really happed???? SEE another crappy drawing.

 

[Iplayfarmer]

A little give and take is always good. Who knows, we may both learn something from this.

But I am still in disagreement with you, sort of. While the angle of the cylinder may indicate "true" vertical force, using that "true" vertical force of ~20000lbs you calculated earlier would assume that the bed is level. BUT the effective angle of the bed is the "green" line. So that "true" vertical component can only be used if the green line is horizintal. (IE: the rear pivot and the cylinder-bed pivot are equal distances below the bed.

To illustrate my point, lets exaggerate a bit. Lets say the cylinder is mounted on a 10* angle and the rear pivot were dropped down REALLY low to create say a 12* "green" line. IE moving the base of the cylinder above the "green" line. The vertical component would still be 17% of the 49000lbs of avaliable force, or about 8000lbs. But what would really happed???? SEE another crappy drawing.

Agreed. In an extreme example, you can extend the bed pivot down ten feet at which point you're no longer lifting the front of the bed up with the cylinder, but you're moving the bed to the left. You've changed the direction of movement relative the the force of gravity. The point being that the position of the rear bed pivot is going to significantly affect the amount of force needed to make the bed move. Eventually you come down to some combination of bed pivot location and ram angle and location.

You're right that by moving the bed pivot you change the force needed. I'm right that by changing the angle of the ram I change the force available. In both cases the ratio of force needed to force available is changed. It's amazing how complex a dump truck becomes when we allow each other to pick it apart like this. I think the discussion is productive, though.

Every discussion of dump beds seems to come down to some fuzzy S.W.A.G. stuff, and eventually trial and error. I can't get any better. It would be nice to have some equation that a guy could plug a few numbers into and know that it's going to take X ft.lbs. of torque to dump powerstroke444e's truck when it's loaded to capacity. Then it's a matter of figuring how many feet away from the pivot the ram has to be and how steep of an angle to get the right amount of dumping force. I've done some head scratching since my last post, and I've figured it's going to have something to do with the linear mass density of a loaded bed and will likely require some calculus. That's why I haven't figured it out yet.

Sorry powerstroke for hijacking your thread. I think we all agree that your ram is at least big enough to dump your truck. We're just trying to figure it out systematically so that someone down the road can review this thread and have all the answers. In any case, keep the pictures and progress updates coming. I'd love to see how you rigged the baffles in your toolboxes.

 

[Iplayfarmer]

But what would really happed???? SEE another crappy drawing.

I realized that I never answered your question. The bed would still dump. It would just be easier.

 

[LD1]

I realized that I never answered your question. The bed would still dump. It would just be easier.

I think you have that backwards. The bed would NOT dump. It would either simply stall the ram aond do nothing, or bend and break things:laughing:

 

[Iplayfarmer]

I think you have that backwards. The bed would NOT dump. It would either simply stall the ram aond do nothing, or bend and break things:laughing:

Yep. You're right. That's a third part of the process that has to be considered.

 

[powerstroke444e]

Seeing you guys like figuring here are the measurements. From front pin on cylinder the back cylinder pin 17 inches down and cylinder is about 32 inches back I think the cylinder measures about 38 long closed and I forgot the lenght extended but its around 90 inches. The hinges are 9 foot from the front pin and 12 inches below. Calc away. All I know is when I pressed the button it when up with very little pressure in the line.

 

[LD1]

Seeing you guys like figuring here are the measurements. From front pin on cylinder the back cylinder pin 17 inches down and cylinder is about 32 inches back I think the cylinder measures about 38 long closed and I forgot the lenght extended but its around 90 inches. The hinges are 9 foot from the front pin and 12 inches below. Calc away. All I know is when I pressed the button it when up with very little pressure in the line.

The cylinder is 32" back from the front of the bed correct????

And the rear hinge is 9' behind that correct?? that right their is 11'8" from front of bed to rear pivot. Is their any overhang?? Total length of the bed???

 

[LD1]

I have attached a drawing. Another crappy one:laughing:

But if I understand you correctly, the dimensions in blue are the ones you just gave me.

In order to figure out the max dump capacity AND the max angle, could you please give the dimensions in red. A and B.

And if you are certain that the cylinder extended length is 90", I can figure the max angle.

Thanks